Suspension systems in vehicles comprise a number of components. Such components include vehicle tires, which deform to absorb bumps and return to previous size; springs, which cushion impact; shock absorbers located between the axle or frame or struts as part of the axle assembly to dampen the effect of impact; and bushings which are placed between the junctions of the above components.
The suspension system in a vehicle provides a variety of functions. Such functions include providing a softer ride for vehicle occupants while traveling over bumps. Additionally, a suspension system must provide stiffness to support a vehicle during travel and provide stability to a vehicle during turns. The various objectives required of a suspension system seemingly demand that the suspension system fulfill conflicting functions. For instance, the suspension system is required to provide a softer ride so that occupants do not feel bumps on a roadway while providing stiffness to support the vehicle and keep it stable. Suspension systems in some circumstances must allow for conformity and be less “stiff” to provide a softer ride for occupants while in other circumstances providing rigidity and stiffness to stabilize a vehicle as is required in vehicle turns.
Previous suspension systems and the like have described a variety of systems to make the ride more comfortable for the occupants of a vehicle. One method of creating a smoother ride is to provide a large profile tire which is used to absorb small deflections and help cushion the ride. As the vehicle encounters a bump, the tire compresses and vehicle occupants do not feel the bump. After the bump, the tire returns to its previous configuration. Similarly, shock absorbers have been made to be soft and easily compressible. Springs have been made to be similarly responsive, and bushings have been made of a soft rubber to absorb impacts as well. However, these modifications to achieve a smooth ride result in very poor handling in a turn as well as making the vehicle ride uncomfortable with the shock absorber or damper taking a very long time to control the oscillations from the springs. When a vehicle enters a corner to make a turn, a number of components of the vehicle compress allowing the vehicle to roll. These include the shock absorber, the bushings, and the sidewall of the tire. Compression of these components reduces the ability of the suspension system to alter and change vehicle momentum thus decreasing the ability of a driver of the vehicle to control it.
In order to address vehicle stability problems, previous systems have described various methods of providing increased stability to a vehicle and creating a stiffer suspension. As previously indicated, the need for increased stability is particularly evident when a vehicle is turning or cornering. One means commonly used to stiffen a suspension system is to equip the vehicle with low profile tires to enhance the cornering of the vehicle. Others may use a low profile tire for aesthetic reasons. A low profile tire has less sidewall distance between the roadway and the rim on which it is mounted so that the flexible component of the tire is reduced. For instance, if a high profile tire would compress three inches when cornering or encountering a bump, a low profile tire may only compress one inch. As these small one-inch deflections (approximately) are encountered the air within the tire is compressed and the rubber of the tire responds by compressing in some areas and expanding to some degree in others. The tire then returns to its normal shape in an elastomeric response and the air returns to its previous pressure level.
Although providing increased stability, the force of an impact is usually fully transmitted to the occupants making the ride less comfortable. The stiffer suspension achieved through the use of low profile tires, stiff shocks, and hard bushings, transmits the forces from small deflections in the road directly to the occupants reducing comfort.
Shock absorbers of the prior art are generally constructed either to be less stiff with the ability to absorb roadway deflections and create a smoother more comfortable ride for the occupants or to be more stiff, providing greater stability to the vehicle, but decreased comfort to the occupants of the vehicle. They cannot incorporate the benefits of comfort and stability into a single shock absorber.
If a suspension is equipped with stiffer shock absorbers, the shock absorber relies on the tire wall to absorb small deflections. However, as small roadway deflections are absorbed by the tire, vehicle occupants begin to experience reduced vehicle handling ability. If a suspension is equipped with softer, less stiff, shock absorbers, such shock absorbers have a decreased ability to return the shock to its pre-impact state and a decreased ability to maintain a stable position. Accordingly, the vehicle will experience a bouncing effect as it encounters larger bumps and deflections in the roadway.
The current invention overcomes limitation of the prior art by providing a single shock absorber which is capable of providing the comfort of a less stiff suspension while providing the benefits of increased stability realized through a stiffer suspension. The shock absorber of the current invention offers the ability to absorb small roadway deflections and return the shock to the resting state without compromising the ability of the shock to provide necessary stiffness for vehicle stability.